<form class="form-horizontal">
  <div class="control-group">
    <label class="control-label" for="inputIcon">Email address</label>
    <div class="controls">
      <div class="input-prepend">
        <span class="add-on"><i class="icon-envelope"></i></span><input class="span2" id="inputIcon" type="text">
      </div>
    </div>
  </div>
</form>
